Possible 7M BHG... opinions please

[BlackSupra]

well with the amount of corroded 7m's around, i won't use anything but toyota genuine red stuff

[whatthe?]

Well, got an A/C pipe made up today and had the car re-gassed. A/C is nice and cold but unfortunately when it's on it causes the overheating problem to come back grrrrrrr. I really dont understand this, It was 43 here today and it can idle in traffic for 1/2 hour without the gauge moving off halfway but turn on the A/C and it goes up real quick. Even boosting has less effect than the stupid freakin' airconditioner! I went to the drags tonight and even 400m at high rpm with pretty much constant 12psi boost doesnt overheat it as much

I also fitted the plastic tray thing that supposedly forces more air through the rad today, no great difference as far as I can tell. Gonna try and find myself a colder TRD thermostat tomorrow and see if that helps. Any other suggestions welcome.

[SL666]

this might sound really stoopid, but is it possible that the thermo on the AC is blowing the wrong way?

and if the thermostat is too cold it might keep the engine in the 'warming up' part of the map use assloads of fuel and go nowhere..

[CrUZida]

Have you got a fan shroud on?
Sounds like the viscous hub might not be locking up enough.

[whatthe?]

Yep, fan shroud is on, fan viscous seems to work pretty well (can't stop the fan turning at idle, it makes a huge whooshing noise when revving the enigine). Just got back from toyota with new 82C thermostat and O ring in hand, apparently the 88C thermostat is more common so maybe thats whats in there and not working all that well. If this fails it's time to get it tested for BHG. Are those Tee Kay tests the guys on the NZ forums carry on about available here?

[rvrolla]

Yes, I had one done in my old MZ20. My local mechanic had one.

[whatthe?]

Well, todays driving test has proven inconclusive. Driving around, idling in traffic, boosting to 10psi repeatedly results in no change to temp gauge, sits on halfway rock steady. However, when I stopped to check the underbonnet situation I noticed lots of little bubbles being produced in the coolant resevoir. I'm taking this as a bad sign.....

The only thing I did that actually raised the temperature was some extremely "spirited" driving on the M4 at 15psi boost. I'm assuming this temp increase was due to leaning out as the SAFC is still zeroed and woulnt be adding extra fuel to the mix

[rvrolla]

The SAFC's usually do the opposite with the 7M's, they run very rich in standard form and the SAFC leans it out a little to give a little extra HP and better fuel econ.

[whatthe?]

The SAFC's usually do the opposite with the 7M's, they run very rich in standard form and the SAFC leans it out a little to give a little extra HP and better fuel econ.

Really? I was told that I shouldnt run more than 11 psi boost (thats where the standard boost cut is) because the standard ecu would be supplying the same fuel at 11psi as at 15 and that would lead to over heating due to leaning out and possible piston/ring damage?

Therefore I assumed that whilst tuning the safc the mixture would have to be richened to counteract this? I can tell that it's running mega rich off boost and even at low boost (due to 550cc injectors) but will it still run rich at 15psi?

[JustCallMeOrlando]

So long as the ECU is fuelling for it, then yeah, it'll be fine. It's when people run fuel cut defenders to let the ECU run more boost than it's mapped for that you have problems.

[SL666]

Really? I was told that I shouldnt run more than 11 psi boost (thats where the standard boost cut is) because the standard ecu would be supplying the same fuel at 11psi as at 15 and that would lead to over heating due to leaning out and possible piston/ring damage?

hmm i think that would happen at about 12 psi if that was the case.. at 15 psi you wouldn't have head gasket issues... you would have distinct lack of pistons in bores..

[whatthe?]

A Tee-Kay test this morning has proven the worst, BHG. I now have 2 cars in my garage with stuffed 7Ms in them. Woohoo! Well, guess I know what I'll be doing this weekend......

[JustCallMeOrlando]

That sucks the big one. Joys of the 7M

[whatthe?]

Yes, but nevermind. Can anyone recommend a good shop for headwork/machining/reboring etc in NSW? The megap00 build is about to begin.....
Guess I should get it engineered with this motor first tho, they may not take kindly to what I'm planning for the next one! I better be quick whilst it still runs

[rvrolla]

Sorry to hear man, but it is expected i spose